Cellular and Circuitry Bases of Autism:Lessons Learned from the Temporospatial Manipulation of Autism Genes in the Brain

Transgenic mice carrying mutations that cause Autism Spectrum Disorders（ASDs） continue to be valuable for determining the molecular underpinnings of the disorders. Recently, researchers have taken advantage of such models combined with Cre-lox P and similar systems to manipulate gene expression over space and time. Thus, a clearer picture is starting to emerge of the cell types, circuits, brain regions, and developmental time periods underlying ASDs. ASD-causing mutations have been restricted to or rescued speci？cally in excitatory or inhibitory neurons, different neurotransmitter systems, and cells speci？c to the forebrain or cerebellum. In addition,mutations have been induced or corrected in adult mice,providing some evidence for the plasticity and reversibility of core ASD symptoms. The limited availability of Cre lines that are highly speci？c to certain cell types or time periods provides a challenge to determining the cellular and circuitry bases of autism, but other technological advances may eventually overcome this obstacle.

Next-generation mapping of the salicylic acid signaling hub and transcriptional cascade

For over 60 years,salicylic acid(SA)has been known as a plant immune signal required for basal and systemic acquired resistance.SA activates these immune responses by reprogramming∼20%of the transcriptome through NPR1.However,components in the NPR1 signaling hub,which appears as nuclear condensates,and the NPR1 signaling cascade have remained elusive due to difficulties in studying this transcriptional cofactor,whose chromatin association is indirect and likely transient.To overcome this challenge,we applied TurboID to divulge the NPR1 proxiome,which detected almost all known NPR1 interactors as well as new components of transcription-related complexes.Testing of new components showed that chromatin remodeling and histone demethylation contribute to SA-induced resistance.Globally,the NPR1 proxiome has a striking similarity to the proxiome of GBPL3 that is involved in SA synthesis,except for associated transcription factors(TFs),suggesting that common regulatory modules are recruited to reprogram specific transcriptomes by transcriptional cofactors,like NPR1,through binding to unique TFs.Stepwise green fluorescent protein-tagged factor cleavage under target and release using nuclease(greenCUT&RUN)analyses showed that,upon SA induction,NPR1 initiates the transcriptional cascade primarily through association with TGACG-binding TFs to induce expression of secondary TFs,predominantly WRKYs.Further,WRKY54 and WRKY70 were identified to play a major role in inducing immune-output genes without interacting with NPR1 at the chromatin.Moreover,loss of condensate formation function of NPR1 decreases its chromatin association and transcriptional activity,indicating the importance of condensates in organizing the NPR1 signaling hub and initiating the transcriptional cascade.Collectively,this study demonstrates how combinatorial applications of TurboID and stepwise greenCUT&RUN transcend traditional genetic methods to globally map signaling hubs and transcriptional cascades for in-depth explorations.